Green sand mold molding sensor and green sand mold moldability evaluation method

ABSTRACT

A casting mold molding machine includes a green sand mold molding sensor including a pressure sensor for evaluating moldability of a green sand mold molded by a casting mold molding machine, wherein the pressure sensor is embedded in a squeeze board or squeeze feet that compresses green sand.

RELATED APPLICATIONS

The present application is a divisional application of U.S. application Ser. No. 17/042,231 filed Sep. 28, 2020, which in turn is a U.S. national stage application of PCT/JP2019/017600 filed Apr. 25, 2019, which claims priority to Japanese Patent Application No. 2018-114249 filed Jun. 15, 2018. Each of these prior applications is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to a green sand mold molding sensor that evaluates the moldability of a green sand mold molded by a casting mold molding machine.

BACKGROUND

One of the indicators for evaluating the quality demanded of a green sand mold (casting mold) molded by a casting mold molding device is casting mold strength. Normally, in order to determine whether a molded green sand mold has sufficient casting mold strength, work is carried out to measure each molded green sand mold individually using a casting mold strength gauge. A method for confirming whether a molded green sand mold has sufficient casting mold strength without having to perform such work is desired. Furthermore, a method for managing the casting mold quality of each molded green sand mold without stopping a process is desired.

For example, Patent Document 1 discloses a method for detecting abnormalities in blowing in and loading of casting sand in a blow-in type casting mold molding machine, wherein an internal pressure is measured by a pressure sensor in order to detect abnormalities in blowing in and loading of casting sand.

Further, Patent Document 2 discloses a molding device monitoring system which discovers defective casting molds by using position sensors for measuring positions of flask-setting cylinders, filling-flask cylinders, and a leveling frame to monitor the height of a parting plane of a casting mold.

CITATION LIST Patent Literature

Patent Document 1: JP 3415497 B

Patent Document 2: JP 3729197 B

SUMMARY OF INVENTION Technical Problem

However, the method for detecting abnormalities in blowing in and loading of casting sand of Patent Document 1 is capable of detecting sand loading defects only and it is difficult to confirm the precise casting mold strength. Further, even if the molding device monitoring system of Patent Document 2 monitors the height of the parting plane of the casting mold, it is difficult to confirm the precise casting mold strength from the height of the parting plane.

The present invention was achieved in light of the foregoing and has the objective of providing a green sand mold molding sensor that, in order to determine the quality of a molded green sand mold, can measure pressure applied to a pressing surface of a squeeze board or squeeze feet that compresses the green sand.

Solution to Problem

In order to solve the problem mentioned above and achieve the objective, the green sand mold molding sensor of the present invention comprises a pressure sensor for evaluating the moldability of a green sand mold molded by a casting mold molding machine, wherein the pressure sensor is embedded in a squeeze board or squeeze feet that compresses green sand.

Further, in one embodiment of the present invention, the squeeze board or squeeze feet is a member that constitutes a part of a boundary of a molding space defined by the squeeze board or squeeze feet and a metal flask during green sand mold molding by the casting mold molding machine.

Further, in one embodiment of the present invention, a pressure-receiving surface of the pressure sensor and a surface of the squeeze board or squeeze feet are in a flush state.

Further, in one embodiment of the present invention, as a member that constitutes a part of a boundary of a molding space defined by the member and a metal flask during green sand mold molding by the casting mold molding machine, the squeeze board or squeeze feet and a plate having attached thereto a pattern arranged facing the squeeze board or squeeze feet are provided, the pressure sensor being embedded in the squeeze board or squeeze feet at a corresponding position between the metal flask and the pattern.

Further, in one embodiment of the present invention, the squeeze board is configured to be rectangular, a plurality of the pressure sensors are provided, and these pressure sensors are embedded in the four corners of the squeeze board.

Further, in one embodiment of the present invention, an arrangement of the squeeze feet is configured to be rectangular, a plurality of the pressure sensors are provided, and these pressure sensors are embedded in any of the squeeze feet including the squeeze feet in the four corners.

Further, in one embodiment of the present invention, the pressure sensor is fixed to the squeeze board or squeeze feet by a screwing means.

Further, in one embodiment of the present invention, the pressure sensor is a fluid sensor.

Further, in one embodiment of the present invention, the size of the pressure-receiving surface of the pressure sensor is 5-30 mm in diameter.

Further, a method for evaluating green sand mold moldability in the present invention evaluates the moldability of a green sand mold molded by a casting mold molding machine by using a green sand mold molding sensor provided with a pressure sensor embedded in a squeeze board or squeeze feet that compresses green sand.

Effects of Invention

The present invention provides an effect wherein, in order to determine the quality of a molded green sand mold, it is possible to measure pressure applied to a pressing surface of a squeeze board or squeeze feet that compresses green sand.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 represents a schematic of a structure of a casting mold molding device using green sand mold molding sensors according to a first embodiment.

FIG. 2 represents a configuration of a portion of a casting mold molding device, wherein the portion evaluates casting mold quality.

FIG. 3 is a cross-section view representing details of a portion of a squeeze board having green sand mold molding sensors embedded therein.

FIG. 4 is a cross-section view representing details of a portion of a squeeze board having green sand mold molding sensors embedded therein.

FIG. 5 is a block diagram representing one example of a functional configuration of a casting mold quality evaluation device.

FIG. 6 is a block diagram representing another example of a functional configuration of a casting mold quality evaluation device.

FIG. 7 is a schematic view representing a configuration of an experiment carried out herein, (a) being cross-section view and (b) being a plan view of a squeeze board.

FIG. 8 is a graph representing one example of results obtained by recording, in an integrated amplifier-recorder, temporal changes in the pressure of a green sand mold molding sensor in a squeezing step and analyzing by computer.

FIG. 9 is a graph summarizing a relationship between peak pressure of a green sand mold molding sensor and casting mold strength.

FIG. 10 shows one example of a screen displayed on a display unit.

FIG. 11 shows one example of a screen displayed on a display unit.

FIG. 12 shows one example of a screen displayed on a display unit.

FIG. 13(a)-(c) show steps in a method for evaluating casting mold quality (method for molding a green sand mold) using the casting mold molding device according to the first embodiment.

FIG. 14 shows another example of a squeeze board having green sand mold molding sensors embedded therein.

FIG. 15 shows another example of a squeeze board having green sand mold molding sensors embedded therein.

FIG. 16 represents a schematic of a structure of a casting mold molding device using green sand mold molding sensors according to a second embodiment.

FIG. 17 represents a configuration of a portion of a casting mold molding device, wherein the portion evaluates casting mold quality.

FIG. 18(a-d) show steps in a method for evaluating casting mold quality (method for molding a green sand mold) using the casting mold molding device according to the second embodiment.

FIG. 19 shows another example of a squeeze board having green sand mold molding sensors embedded therein.

FIG. 20 shows another example of a squeeze board having green sand mold molding sensors embedded therein.

FIG. 21(a) and (b) represent a schematic of a structure of a casting mold molding device according to a third embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, reference is made to the attached drawings to describe embodiments for implementing the green sand mold molding sensor and the method for evaluating green sand mold moldability according to the present invention.

First Embodiment

The first embodiment will be described with reference to the attached drawings. FIG. 1 represents a schematic of a structure of a casting mold molding device using green sand mold molding sensors according to the first embodiment and FIG. 2 represents a configuration of a portion of the casting mold molding device, wherein the portion evaluates casting mold quality. The casting mold molding device according to the present embodiment is a flask molding machine in which, after a green sand mold (casting mold) is molded, a casting flask (metal flask), with the green sand mold contained therein, transfers to the next step.

A casting mold molding device 1 comprises a plate 2 having a pattern 3 attached to an upper surface thereof, a carrier 4, a metal flask 5, a filling flask 6, a squeeze head 7, a squeeze board 8, a table 9, green sand mold molding sensors 10A, 10B, 10C, 10D, wiring 11, and a casting mold quality evaluation device 12. Note that FIG. 2 represents the green sand mold molding sensors 10A, 10B, 10C, 10D of the squeeze board 8 as seen when viewed from the line A-A of FIG. 1 (view taken along line A-A of FIG. 1).

The plate 2 has attached to an upper surface thereof an upper mold (or lower mold) pattern 3 for molding a shape of a casting in a green sand mold. The plate 2 is formed from aluminum, for example. The carrier 4 is flask shaped and the plate 2 is placed inside the flask. In addition, green sand for molding a green sand mold is loaded into a casting mold molding space surrounded by the plate 2, the metal flask 5, the filling flask 6, and the squeeze board 8. The squeeze board 8 is rectangular and is a member that constitutes a part of the boundary of the molding space defined by the squeeze board 8 and the metal flask 5 during green sand mold molding by the casting mold molding device 1.

For the loading of green sand by the casting mold molding device 1, a gravity drop method that uses the weight of the green sand or a blowing method that uses an airflow is employed. The gravity drop method is a method for loading green sand into the casting mold molding space by causing green sand accumulated in a louvered hopper (not shown) disposed at an upper portion of the casting mold molding device 1 to drop due to gravity. Further, the blowing method is a method for loading green sand by blowing green sand inside a sand tank (not shown) into the casting mold molding space.

Here, there follows a brief description of a procedure for loading green sand into the casting mold molding space and compressing. First, the metal flask 5 is placed on top of the carrier 4 and then the filling flask 6 is overlaid on top of the metal flask 5 to define the casting mold molding space. Next, green sand is loaded into the casting mold molding space and the squeeze board 8 compresses (squeezes) the green sand. Due thereto, the green sand in the casting mold molding space is tamped and a green sand mold is molded.

(Green Sand Mold Molding Sensor)

The green sand mold molding sensors 10A, 10B, 10C, 10D measure, during molding of a green sand mold, a pressure value (peak pressure) applied to a pressing surface between the squeeze board 8 and the green sand inside the casting mold molding space. The green sand mold molding sensors 10A, 10B, 10C, 10D are pressure sensors. In the present embodiment, the green sand mold molding sensors 10A, 10B, 10C, 10D are embedded in the four corners of the squeeze board 8. The reason, which is described later, that the green sand mold molding sensors 10A, 10B, 10C, 10D are embedded in such a way is a result of considering the variation in pressure applied to the pressing surface of the squeeze board 8. By embedding the green sand mold molding sensors 10A, 10B, 10C, 10D in the four corners of the squeeze board 8, it is possible to see the strength distribution of the entire casting mold.

In addition, the green sand mold molding sensors 10A, 10B, 10C, 10D have a pressure-receiving surface for measuring pressure that is exposed in the pressing surface of the squeeze board 8 and measures the pressure value (peak pressure) applied to the pressing surface between the squeeze board and the green sand mold. At this time, it is desirable for the pressure-receiving surface of the green sand mold molding sensors 10A, 10B, 10C, 10D and the pressing surface of the squeeze board 8 to be in a flush state with no differences in level therebetween. Due thereto, it is possible to measure the precise pressure. In one example, the green sand mold molding sensors 10A, 10B, 10C, 10D are fluid pressure sensors. An earth pressure sensor may also be used as the green sand mold molding sensors 10A, 10B, 10C, 10D.

Further, regarding the green sand mold molding sensors 10A, 10B, 10C, 10D, a small pressure-receiving surface makes it easier to match casting mold strength measurement positions in the green sand mold facing positions where pressure was measured, considering the size of the squeeze board 8 in which the sensors are embedded and the shape of the pattern 3, and moreover, that, as described later, the casting mold strength of a formed green sand mold is measured by a casting mold strength gauge at positions of the plate 2 facing positions of the squeeze board 8 where the green sand mold molding sensors 10A, 10B, 10C, 10D measured the pressure, and that a relationship between the pressure value (peak pressure) and the casting mold strength is utilized. Meanwhile, since measurement accuracy is also demanded, with respect to the size of the pressure-receiving surface, a diameter of approximately 5-30 mm is desirable.

FIG. 3 and FIG. 4 are lateral cross-section views representing details of a portion of the squeeze board 8 that has green sand mold molding sensors 10A, 10B, 10C, 10D embedded therein. FIG. 3 represents a case wherein the green sand mold molding sensors 10A, 10B, 10C, 10D are of a threaded type. As shown in FIG. 3, a male thread is formed in a of the green sand mold molding sensors 10A, 10B, 10C, 10D, a female thread is formed in b of the squeeze board 8, and the green sand mold molding sensors 10A, 10B, 10C, 10D are screwed to the squeeze board 8.

Meanwhile, FIG. 4 represents a case wherein the green sand mold molding sensors 10A, 10B, 10C, 10D are of a disk shape. As shown in FIG. 4, the green sand mold molding sensors 10A, 10B, 10C, 10D, are placed in a hole in the squeeze board 8 and a ring-shaped liner 13 surrounds the outer edge of the green sand mold molding sensors 10A, 10B, 10C, 10D. In addition, bolts 14 fix the liner 13 and retain the green sand mold molding sensors 10A, 10B, 10C, 10D.

Thus, for the green sand mold molding sensors 10A, 10B, 10C, 10D, it is also possible to use an object having a specification of either a threaded type or a disk shape and that selection may be made with consideration given to an embedding space and attachability of the green sand mold molding sensors.

The wiring 11 connects the casting mold quality evaluation device 12 to the green sand mold molding sensors 10A, 10B, 10C, 10D. In the present embodiment, the green sand mold molding sensors 10A, 10B, 10C, 10D and the casting mold quality evaluation device 12 are connected by wire (wired communication) via the wiring 11 but may also be connected wirelessly (wireless communication). For example, it is possible to amplify, by means of an amplifier, for example, the pressure value (pressure value data) detected by the green sand mold molding sensors 10A, 10B, 10C, 10D and use wireless communication such as a wireless LAN or Bluetooth®, etc., to transmit from a transmitter to the casting mold quality evaluation device 12.

(Casting Mold Quality Evaluation Device)

The casting mold quality evaluation device 12 evaluates the quality of a green sand mold molded by the casting mold molding device 1 from the pressure value (pressure value data) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D. FIG. 5 is a block diagram representing a functional configuration of the casting mold quality evaluation device 12 for wired communication data. The casting mold quality evaluation device 12 comprises a receiving unit 15, an amplification unit 16, an input unit 17, a casting mold strength calculation unit 18, a casting mold quality determination unit 19, a display unit 20, a transmission unit 21, and a recording unit 22.

The receiving unit 15 receives the pressure value (pressure value data) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D. In the present example, wired data is received from the wiring 11.

The amplification unit 16 amplifies the signal amount of the received pressure value (pressure value data). The amplification unit 16 is, for example, an amplifier.

The input unit 17 inputs: the casting mold strength of a molded green sand mold measured by a casting mold strength gauge; values of a slope “a” and an intercept “b” in an expression y=ax+b described later; and a threshold value of the casting mold strength of a green sand mold to be molded. Note that inputting is carried out by a worker. The input unit 17 is, for example, a keyboard or a touch panel. In the expression y=ax+b, “y” is the casting mold strength and “x” is the pressure value measured by the green sand mold molding sensors 10A, 10B, 10C, 10D. The expression is a relational expression for determining the casting mold strength “y” from the slope “a” and the intercept “b” which were inputted and a measured value “x”.

From the slope “a” and the intercept “b”, which were inputted into the input unit 17, and from the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D, the casting mold strength calculation unit 18 calculates the casting mold strength for each pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D by using the relational expression between the measured value and the casting mold strength. A method for calculating the casting mold strength is described in detail later. The casting mold strength calculation unit 18 is, for example, a computer or a PLC.

The casting mold quality determination unit 19 determines the quality of a molded green sand mold from the threshold value of the casting mold strength inputted into the input unit 17 and the calculated casting mold strength. A method for determining the casting mold quality is described in detail later. The casting mold quality determination unit 19 is, for example, a computer or a PLC.

The display unit 20 displays: the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D; values of the slope “a” and the intercept “b” in the relational expression y=ax+b between the casting mold strength inputted by a worker using the input unit 17 and the pressure value (peak pressure); the threshold value of the casting mold strength of a green sand mold to be molded that was inputted by a the worker; a casting mold strength calculation result; and a casting mold quality determination result, etc. The display unit 20 is, for example, a liquid crystal display, etc.

The transmission unit 21 transmits fault-determination data to a Patlite® 23, etc. Transmission may be either by wired data or wireless data. In addition, a worker that has recognized a defect occurrence in a green sand mold by confirming that the Patlite 23 is flashing, etc., is to make an X mark on the relevant green sand mold and thereby make it possible to understand at a glance that that green sand mold is a defective product. A green sand mold that has been recognized as being a defective product does not undergo subsequent steps (molten metal pouring) and after skipping these steps is finally shaken out from the mold.

The recording unit 22 records pressure value data, casting mold strength data associated with pressure values, casting mold strength calculation results, and casting mold quality determination results, etc. Furthermore, these data are recorded for each pattern attached to the plate 2. The recording unit 22 is, for example, a recording medium such as a semiconductor memory or a magnetic disk, etc. In addition, the data recorded by the recording unit 22 may be extracted by using a USB memory or an SD card, etc.

As described earlier, the green sand mold molding sensors 10A, 10B, 10C, 10D and the casting mold quality evaluation device 12 may be connected wirelessly (wireless communication). FIG. 6 is a block diagram representing a functional configuration in the case wherein the pressure value (pressure value data) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D is connected wirelessly (wireless communication) to the casting mold quality evaluation device 12. The pressure value (pressure value data) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D is amplified by an amplification unit 16′ near the green sand mold molding sensors and wirelessly transmitted from a pressure value transmission unit 24 to a receiving unit 15′ of the casting mold quality evaluation device 12. The casting mold quality evaluation device 12 for wireless data shown in FIG. 6 comprises a receiving unit 15′, the input unit 17, the casting mold strength calculation unit 18, the casting mold quality determination unit 19, the display unit 20, the transmission unit 21, and the recording unit 22.

After the pressure value (pressure value data) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D has been amplified by the amplification unit 16′, the receiving unit 15′ receives wireless data transmitted from the pressure value transmission unit 24. Note that the functions of the input unit 17, the casting mold strength calculation unit 18, the casting mold quality determination unit 19, the display unit 20, the transmission unit 21, and the recording unit 22 are the same as the functions of the casting mold quality evaluation device 12 for wired data described earlier.

(Relationship Between Pressure Measured by Green Sand Mold Molding Sensors and Casting Mold Strength of Molded Green Sand Mold)

Next, there follows a description of the relationship between the casting mold strength of a molded green sand mold and the pressure value (peak pressure) that is applied to the pressing surface of the squeeze board and measured by the green sand mold molding sensors. In order to investigate the relationship between the foregoing, an experiment was carried out by using a molding machine. FIG. 7 shows a schematic view representing a configuration of an experiment carried out herein, (a) being a cross-section view and (b) being a plan view of a squeeze board. The cross-section view shown in FIG. 7(a) has the pattern 3 arranged therein, but the experiment was carried out for cases in which the pattern 3 is attached and for cases in which the pattern 3 is not attached. Further, the plan view of the squeeze board 8 of FIG. 7(b) represents: a positional relationship between the squeeze board and the sensors; an integrated amplifier-recorder 25 that amplifies and records signals from the pressure sensors; and a computer 26 that is connected to the integrated amplifier-recorder 25 and performs analysis such as graphing sensor measurement values. The experiment was performed as follows.

1. Green sand mold molding sensors were installed (embedded) in a squeeze board. As shown in FIG. 7, installation locations were set at a total of three locations: in the central section (S3) of the squeeze board and in two corner locations (S1, S2) sandwiching the central section. Further, the present experiment was carried out for cases in which the pattern is attached and for cases in which the pattern is not attached.

2. A green sand mold was molded by a molding machine having green sand mold molding sensors installed in the squeeze board. In addition, during a squeezing step, the pressure applied to the pressing surface of the squeeze board was measured by the green sand mold molding sensors at the three locations. Temporal changes in the pressure value were measured and recorded. With respect to squeezing, pressure was applied gradually up to a set pressure and was released when the set pressure was reached.

3. The casting mold strength of a green sand mold at a parting plane facing the positions where the green sand mold molding sensors measured the pressure was measured by a casting mold strength gauge and the relationship between the pressure value and the casting mold strength was investigated. Note that in the case in which the pattern was attached, the casting mold strength at the parting plane facing the position where the pressure was measured by the green sand mold molding sensor in the central section (S3) is the casting mold strength at the upper surface of the pattern. Further, with respect to the strength gauge that measured the casting mold strength, an invasive-type casting mold strength gauge that is widely used in casting mold factories to evaluate moldability of a green sand mold and that measures the casting mold strength by introducing, approximately 10 mm into the casting mold, a needle having a tip diameter of approximately 3 mm was used.

In addition, the abovementioned 2 and 3 were carried out on a plurality of green sand molds and the data were collected.

(Experimental Results)

FIG. 8 is a graph representing one example showing temporal changes in the pressure of a green sand mold molding sensor in the squeezing step. Note that FIG. 8 represents the case in which there was no pattern, squeezing pressure was set at 0.6 MPa, and measurements were made by sensors at three locations. As shown in FIG. 8, in this molding machine, the peak pressure was reached in the squeezing step approximately three seconds after squeezing commenced.

Further, upon confirming the relationship between the position of the green sand mold molding sensor and the peak pressure, it was understood that the pressure at the central section (S3) of the squeeze board is low and pressure becomes high at the squeeze board periphery (S1, S2). This enabled it to be confirmed that because the squeeze board periphery is near the metal flask wall, the green sand is tamped due to frictional resistance between the green sand and the metal flask whereas the central section (S3) is removed from the metal flask wall, there is no tamping due to the influence of the metal flask, and therefore pressure becomes low compared to the periphery. With respect to the peak pressure of a molding sensor when a pattern is provided, it was understood that, compared to in a corner, the degree of tamping of green sand on the pattern is large, and thus, the peak pressure at the central section (S3) becomes high, the squeezing force is consumed at this portion, the squeezing force at the periphery decreases, and therefore the peak pressure is low at the periphery (S1, S2).

FIG. 9 is a graph summarizing, upon having repeated the abovementioned experiment, the relationship between the casting mold strength and the peak pressure of the green sand mold molding sensors which varies with the set squeezing pressure and the loading state of the green sand. FIG. 9 plots, for each of the central section (S3) and the periphery (S1, S2) with the presence or absence of a pattern, the peak pressure of the pressing surface of the squeeze board and the measurement value of the casting mold strength of the green sand mold at the parting plane facing positions where the pressure was measured. Looking at the relationship between the peak pressure of the green sand mold molding sensors and the casting mold strength of the green sand mold at the parting plane facing positions where the pressure was measured shown in FIG. 9, it is found that with respect to the points corresponding to the periphery (S1, S2), the influence of the presence or absence of a pattern is extremely small and there is a high correlation. Meanwhile, for the points corresponding to the central section (S3), the relationship differed depending on the presence or absence of a pattern: compared to the case of there being no pattern, when a pattern was provided, a tendency for the casting mold strength to be high with respect to the peak pressure was demonstrated.

Summarizing the above results, the pressure reaching the pressing surface of the squeeze board varies depending on whether the position is the periphery or the central section and on the presence or absence of a pattern. The casting mold strength at positions facing the squeeze board has a positive correlation with the pressure reaching the pressing surface of the squeeze board. However, it was clarified that with respect to the central section, the relationship differs depending on the presence or absence of a pattern whereas the periphery is not influenced by the presence or absence of a pattern.

With respect to the relationship between the loading density of green sand and the casting mold strength, when the loading density is high, the casting mold strength becomes high. The loading density and the casting mold strength have a strong positive correlative relationship with tamping force. The peak pressure measured by the molding sensors is synonymous with tamping force. Therefore, when the peak pressure is high, a high loading density is achieved. When the loading density of a molded green sand mold is low, in other words, when the casting mold strength is low, there is a concern of defects such as molten metal infiltration, sand drop/sand inclusion, molten metal leakage, etc. Further, when the loading density of a molded green sand mold is too high, sliding resistance between the pattern and the casting mold increases and there is a concern of mold removal defects. As such, keeping the detected peak pressure of the green sand mold molding sensors at a suitable level leads to a reduction in defects.

(Arrangement Position of Green Sand Mold Molding Sensors)

The pressure conveyed to the green sand mold molding sensors embedded in the squeeze board varies due to the causes mentioned above and therefore the embedding positions of the green sand mold molding sensors must be places where it is possible to ascertain these circumstances. Accordingly, if multiple green sand mold molding sensors are installed, it is possible to detect flaws under more conditions. However, due to space constraints and from an economic perspective, this is not realistic and it is desirable to be able to detect and evaluate pressure using a smaller number of sensors.

As mentioned earlier, for the loading of green sand by the casting mold molding device 1, a gravity drop method or a blowing method that uses an airflow is employed. In the gravity drop method that uses a louvered hopper, etc., mentioned earlier, a bias when the green sand is loaded into the louvered hopper may become a bias when loading into the casting mold molding space. Further, in the blowing method, a bias may occur when loading into the casting mold molding space due to circumstances such as the distance from the blowing-in nozzle, sand blockage in the nozzle opening, etc. These biases appear as biases in tamping pressure by the squeeze board 8 on the green sand at subsequent tamping of the green sand. It is necessary to arrange the green sand mold molding sensors by taking into consideration the occurrence of such biases in initial loading amounts.

In addition, in cases in which a difference in the measurement value of an arranged green sand mold molding sensor is outside a predetermined threshold value range, it can be determined that the bias of the initial loading is large and it is possible to take measures such as: improving the state in which casting mold sand is loaded into the louvered hopper; adjusting blowing-in air pressure or blowing-in time; or improving the state (blockage, abrasion, etc.) of the blowing-in nozzle. Further, the flowability of the green sand has an influence when the casting mold sand is loaded into the louvered hopper, when loaded from the louvered hopper to the casting mold molding space, or when blown-in by means of blowing, etc. This flowability of the green sand varies according to sand properties such as the water content of the green sand and it is therefore possible to adjust the sand by using a sand processing device such as a kneading machine that kneads green sand to be supplied to the casting mold molding device 1.

Further, when green sand is tamped, the green sand is compressed by a tamping force and a pressure is detected by the green sand mold molding sensors embedded in the squeeze board. As shown in the experimental results above, it was confirmed that the relationship between the pressure detected by the green sand mold molding sensors embedded in the squeeze board and the casting mold strength at positions facing the squeeze board differs in the central section depending on the presence or absence of a pattern, but is not influenced in periphery by the presence or absence of a pattern.

As such, in order to evaluate the casting mold strength by the magnitude of the tamping force of the squeeze board, it is preferable to dispose green sand mold molding sensors near the casting flask side surface, which is not influenced by the presence or absence of a pattern, in particular, in the corner sections. If a measurement value of a green sand mold molding sensor disposed in this position does not reach a predetermined lower limit threshold value, it can be judged that a sufficient casting mold strength has not been reached and measures to increase the tamping force can be taken. If the measurement value is higher than an upper limit threshold value, it can be judged that the casting mold strength is more than sufficient and measures to decrease the tamping force can be undertaken.

In the present embodiment, considering the step for loading the green sand and the step for tamping the green sand, the green sand mold molding sensors 10A, 10B, 10C, 10D are embedded in the four corners of the squeeze board 8.

Note that the relationship between the peak value of the pressure of the green sand mold molding sensors and the casting mold strength is also the same when using another type of flask molding machine or a flaskless molding machine. As such, this relationship can also be applied in a casting mold molding device of a second embodiment which is described later.

(Method for Calculating Casting Mold Strength)

Next, there follows a description of a method for calculating the casting mold strength by using the casting mold strength calculation unit 18. As mentioned above, it has been ascertained that there is a correlative relationship between the casting mold strength and the peak value of the pressure of the green sand mold molding sensors. The casting mold strength calculation unit 18 uses this relationship to calculate the casting mold strength from the casting mold strength inputted into the input unit 17 and the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D.

Specifically, calculation of the casting mold strength by the casting mold strength calculation unit 18 comprises two steps.

Step 1

A predetermined number of green sand molds are molded in advance and a pressure value (peak pressure) during squeezing is measured by the green sand mold molding sensors 10A, 10B, 10C, 10D. Furthermore, the casting mold strength at the parting plane facing positions in each of the molded green sand molds where the pressure was measured by the green sand mold molding sensors 10A, 10B, 10C, 10D is measured and inputted into the input unit 17 by a worker. In addition, a worker determines the expression y=ax+b from the relationship between the casting mold strength and the pressure value (peak pressure).

Note that in the present embodiment, on the basis of the experimental results mentioned above, the green sand mold molding sensors 10A, 10B, 10C, 10D are embedded in the four corners of the squeeze board 8. By measuring the pressure applied to the pressing surface of the squeeze board at these four locations and determining the relationship with the casting mold strength, it is possible to determine casting mold quality by using a small number of green sand mold molding sensors and taking into consideration variation in pressure at the pressing surface of the squeeze board. Further, when making a predetermined number of moldings, by varying the squeezing pressure, it is possible to determine the relationship between the pressure applied to the pressing surface and the casting mold strength over a wider range.

FIG. 10 shows one example of a screen displayed on the display unit 20. In the present example, first, a predetermined green sand mold is molded and seven pressure values (peak pressures) measured by the green sand mold molding sensors 10A, 10B at that time are displayed on the screen. Note that it is also possible to switch to a screen which displays seven pressure values (peak pressures) measured by the green sand mold molding sensors 10C, 10D, and that furthermore, one screen may be configured so that seven pressure values (peak values) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D are displayed on the screen.

In addition, the casting mold strength at the parting plane facing positions in each of the molded green sand molds where the green sand mold molding sensors 10A, 10B, 10C, 10D were arranged is inputted as an input value by a worker. Here, “Peak pressure A” and “Casting mold strength A” shown in FIG. 10 are, respectively, the peak pressure value of the green sand mold molding sensor 10A and the casting mold strength at the position of the green sand mold molding sensor 10A. Further, “Peak pressure B” and “Casting mold strength B” in the FIG. 10 are, respectively, the peak pressure value of the green sand mold molding sensor 10B and the casting mold strength at the position of the green sand mold molding sensor 10B; “Peak pressure C” and “Casting mold strength C” displayed on the switched screen are, respectively, the peak pressure value of the green sand mold molding sensor 10C and the casting mold strength at the position of the green sand mold molding sensor 10C; and “Peak pressure D” and “Casting mold strength D” displayed on the switched screen are, respectively, the peak pressure value of the green sand mold molding sensor 10D and the casting mold strength at the position of the green sand mold molding sensor 10D.

The casting mold strength calculation unit 18 plots the casting mold strength and the peak value of the pressure of the green sand mold molding sensors on a graph (in the present example, 7×4=28 places). In addition, when a worker inputs predetermined values for the slope “a” and the intersect “b” of the expression, a straight line y=ax+b is displayed. While confirming the plots, a worker changes numerical values of the slope “a” and the intersect “b”, as appropriate, and upon determining that there is a linear correlation among the plots, determines a final expression y=ax+b. Note that if there are no problems in terms of casting mold strength with a green sand mold for which the casting mold strength has been measured by a worker, it is possible for manufacturing to proceed as-is by carrying out subsequent steps (core setting step, molten metal pouring step, etc.). Note also that in the above description, a worker inputted the slope “a” and the intersect “b” of the expression, but these may also be determined by using a computer or a PLC and performing a linear regression by a least-squares method, etc.

Step 2

After determining the expression y=ax+b, molding of the green sand mold commences. After commencing, the expression y=ax+b is used to automatically calculate the casting mold strength at the positions of the green sand mold molding sensors 10A, 10B, 10C, 10D from the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D. Due thereto, there is no need for a worker to measure the casting mold strength separately.

Note that in the present example, the casting mold strength is measured using a casting mold strength gauge and the number of peak pressures and casting mold strengths displayed on the screen is seven each for A and B. However, this may be changed, as appropriate, according to the specifications of the casting mold molding device 1, specifications such as shape and size of the green sand mold to be molded, etc., or the specifications of the green sand.

(Method for Determining Casting Mold Quality)

Next, there follows a description of a method for determining casting mold quality by using the casting mold quality determination unit 19. The casting mold quality determination unit 19 determines the quality of a green sand mold from the threshold value of the casting mold strength inputted into the input unit 17 and the casting mold strength calculated by the casting mold strength calculation unit 18.

Specifically, determination of the casting mold quality by the casting mold quality determination unit 19 comprises two steps.

Step 1

First, a worker inputs a threshold value of the casting mold strength of a green sand mold to be molded. FIG. 11 shows one example of a screen displayed on the display unit 20. In the present example, specific threshold values inputted by a worker are displayed. Here, “Sensor A strength normal range” in FIG. 11 indicates the lower limit value and the upper limit value of the casting mold strength at the position of the green sand mold molding sensor 10A; “Sensor B strength normal range” in FIG. 11 indicates the lower limit value and the upper limit value of the casting mold strength at the position of the green sand mold molding sensor 10B; “Sensor C strength normal range” in FIG. 11 indicates the lower limit value and the upper limit value of the casting mold strength at the position of the green sand mold molding sensor 10C; and “Sensor D strength normal range” in FIG. 11 indicates the lower limit value and the upper limit value of the casting mold strength at the position of the green sand mold molding sensor 10D. Further, “Casting mold strength difference (Max.−Min.) abnormality value” shown in FIG. 11 indicates a threshold value wherein the difference between the maximum and minimum values of the casting mold strength determined from the pressure value of the green sand mold molding sensors 10A, 10B, 10C, 10D is set as an abnormality value. In the present example, the lower limit value of the casting mold strength at the position of the green sand mold molding sensors 10A, 10B, 10C, 10D is set as 10.0 (N/cm²), the upper limit value of the same is set as 20.0 (N/cm²), and the threshold value wherein the difference between the maximum value and the minimum value of the casting mold strength at the position of the green sand mold molding sensors 10A, 10B, 10C, 10D is set as an abnormality value is set as 5.0 (N/cm²).

Step 2

After the expression y=ax+b is determined by the casting mold strength calculation unit 18 and the threshold value of the casting mold strength is inputted, molding of the green sand mold commences. After commencing, the casting mold strength at the position of the green sand mold molding sensors 10A, 10B, 10C, 10D is automatically calculated from the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D. In addition, the quality of a green sand mold is determined from the inputted threshold value of the casting mold strength and the calculated casting mold strength. Here, determination of the quality of a green sand mold is performed as follows.

In the present example, the threshold values of the casting mold strength A, the casting mold strength B, the casting mold strength C, and the casting mold strength D are each set as 10.0 (N/cm²) or more and 20.0 (N/cm²) or less, and the abnormality threshold value of the difference between the maximum value and the minimum value of the casting mold strength at the positions of the green sand mold molding sensors 10A, 10B, 10C, 10D is set as 5.0 (N/cm²) or more. Accordingly, in the case in which the casting mold strength at the position of the green sand mold molding sensor 10A is 13.0 (N/cm²), the casting mold strength at the position of the green sand mold molding sensor 10B is 12.0 (N/cm²), the casting mold strength at the position of the green sand mold molding sensor 10C is 16.0 (N/cm²), and the casting mold strength at the position of the green sand mold molding sensor 10D is 14.0 (N/cm²), the casting mold strength A, the casting mold strength B, the casting mold strength C, and the casting mold strength D are all within the threshold values. Furthermore, the maximum value of the casting mold strengths A, B, C, D is 16.0 (N/cm²), the minimum value is 12.0 (N/cm²), and the difference between the maximum and the minimum is 4.0 (N/cm²), which is within the range, and therefore the casting mold quality determination unit 19 determines that the casting mold quality is OK.

In contrast thereto, in the case in which the casting mold strength at the position of the green sand mold molding sensor 10A is 11.0 (N/cm²), the casting mold strength at the position of the green sand mold molding sensor 10B is 17.0 (N/cm²), the casting mold strength at the position of the green sand mold molding sensor 10C is 12.0 (N/cm²), and the casting mold strength at the position of the green sand mold molding sensor 10D is 16.0 (N/cm²), the casting mold strength A, the casting mold strength B, the casting mold strength C, and the casting mold strength D are all within the threshold values. However, the maximum value of the casting mold strengths A, B, C, D is 17.0 (N/cm²), the minimum value is 11.0 (N/cm²), and the difference between the maximum and the minimum is 6.0 (N/cm²), which is not within the range, and therefore the casting mold quality determination unit 19 determines that the casting mold quality is faulty.

FIG. 12 shows one example of a screen displayed on the display unit 20. Here, “Peak pressure A”, “Peak pressure B”, “Peak pressure C”, and “Peak pressure D” in FIG. 12 indicate, respectively, the peak pressure value of the green sand mold molding sensor 10A, the peak pressure value of the green sand mold molding sensor 10B, the peak pressure value of the green sand mold molding sensor 10C, and the peak pressure value of the green sand mold molding sensor 10D. Further, “Casting mold strength A”, “Casting mold strength B”, “Casting mold strength C”, and “Casting mold strength D” indicate, respectively, the casting mold strength at the position of the green sand mold molding sensor 10A calculated by the casting mold strength calculation unit 18, the casting mold strength at the position of the green sand mold molding sensor 10B calculated by the casting mold strength calculation unit 18, the casting mold strength at the position of the green sand mold molding sensor 10C calculated by the casting mold strength calculation unit 18, and the casting mold strength at the position of the green sand mold molding sensor 10D calculated by the casting mold strength calculation unit 18.

Furthermore, “Casting mold strength difference (Max.−Min.)” in FIG. 12 indicates the difference between the maximum value and the minimum value of the casting mold strengths A, B, C, D. Further, “Determination” in FIG. 12 indicates a determination result for the casting mold quality by the casting mold quality determination unit 19.

Note that on the screen of the display unit 20 in FIG. 12, a poor numerical value is displayed by shading or coloring the inside of a cell, and OK (normal) and FT (faulty) can be understood at a glance.

Note that the threshold values and the difference between the maximum value and the minimum value set for the casting mold strength A, the casting mold strength B, the casting mold strength C, and the casting mold strength D are determined, as appropriate, in accordance with the specifications of the casting mold molding device 1, specifications such as shape, size, etc., of the green sand mold to be molded, the site of the green sand mold, or the specifications of the green sand, etc. In addition, these values are associated with a pattern number.

In the casting mold molding device 1 of the present embodiment, even if the specifications such as shape, size, etc., of a green sand mold to be molded change, in each case, it is possible for the casting mold strength calculation unit 18 to calculate the casting mold strength and for the casting mold quality determination unit 19 to determine the quality of the molded green sand mold from the calculated casting mold strength.

Further, in the present embodiment, determination of OK (normal) or FT (faulty), etc., is made using a calculated value of the casting strength but is not limited thereto. A positive correlative relationship has been confirmed between pressure values of the green sand mold molding sensors and casting mold strength. Therefore, a pressure value of a green sand mold molding sensor may be used as a reference for determining the casting mold quality directly without carrying out a casting mold strength calculation from the pressure value of the green sand mold molding sensor. For example, with respect to the values in the threshold value table of FIG. 11 which serve as determination references for casting mold quality, each value is a predetermined threshold value set for the pressure value of a green sand mold molding sensor, and a measured pressure value of a green sand mold molding sensor may be determined to be OK (normal) or FT (faulty) by referring to this table.

(Method for Evaluating Casting Mold Quality Using Casting Mold Molding Device)

Next, there follows a description of a method for evaluating casting mold quality (method for molding a green sand mold) using the casting mold molding device 1. FIG. 13 shows steps in a method for evaluating casting mold quality (method for molding a green sand mold) using the casting mold molding device 1 according to the first embodiment. Note that in FIG. 13, a louvered hopper 27 is coupled to the squeeze head 7 of the casting mold molding device 1 shown in FIG. 1. The louvered hopper 27 has a structure wherein a predetermined amount of green sand is loaded therein from a green sand transportation device (not shown) and, after having been briefly retained, louvers 28 at a lower portion of the louvered hopper 27 open and the green sand is loaded into the casting mold molding space.

Molding of a green sand mold by the casting mold molding device 1 follows the procedure described below.

1. When molding is commenced, a table 9 rises and thereby a state shown in FIG. 13(a) is achieved. At this time, a predetermined amount of green sand is loaded into the louvered hopper 27 from the green sand transportation device (not shown).

2. Then, as shown in FIG. 13(b), the louvers 28 at a lower portion of the louvered hopper 27 open and the green sand inside the louvered hopper 27 is loaded into the casting mold molding space defined by the plate 2, the metal flask 5 and the filling flask 6.

3. Then, as shown in FIG. 13(c), the coupled squeeze head 7 and louvered hopper 27 move, the squeeze board 8 is arranged directly above the casting mold molding space, and next, the table 9 rises and thereby the green sand inside the casting mold molding space is squeezed (compressed). At this time, the green sand mold molding sensors 10A, 10B, 10C, 10D measure the pressure value (peak pressure) at the pressing surface of the squeeze board. Note that the casting mold is molded in the present step. At this time, the green sand mold molding sensors 10A, 10B, 10C, 10D are between the wall of the metal flask 5 of the squeeze board 8 and the pattern 3.

4. The pressure value (peak pressure) at the pressing surface of the squeeze board is transmitted to the casting mold quality evaluation device 12 and the quality of the green sand mold that has just been molded is evaluated.

Quality evaluation by the casting mold quality evaluation device 12 is performed after the expression y=ax+b, which represents the relationship between casting mold strength and the peak value of the pressure of the green sand mold molding sensors, has been determined in advance. In addition, a green sand mold determined to be OK by the casting mold quality evaluation device 12 flows, as-is, along the line and subsequent steps (molten metal pouring, etc.) are carried out. Meanwhile, a green sand mold determined to be faulty by the casting mold quality evaluation device 12 flows, as-is, along the line, but subsequent steps (molten metal pouring, etc.) are not carried out. The green sand mold skips these steps and, as a casting mold to be discarded, is shaken out from the mold in the same way as a green sand mold having a casting mold quality evaluation determined as being OK. Thus, it is possible to make a determination of “good” or “poor” with respect to the quality of a molded casting mold for each flask, which can therefore lead to a casting mold quality assurance for each flask. Further, it is possible to judge a defect at the time of molding a green sand mold and therefore it is possible to reduce defects in castings produced. Furthermore, it is possible to omit unnecessary work and therefore it is possible to reduce production costs.

5. Then, in the casting mold molding device 1, the table 9 lowers, the filling flask 6 separates from the metal flask 5 upper surface, and when the table lowers further, the metal flask 5 containing the green sand mold is placed on a roller conveyor connected to subsequent steps such as core-setting, molten metal pouring, etc., the pattern 3 is removed from the green sand mold, and the lowering of the table 9 stops. Next, the metal flask 5 containing the green sand mold is conveyed on the roller conveyor to a subsequent step and the metal flask 5 is loaded into the casting mold molding device 1 in preparation for the next molding. Note that when the lowering of the table 9 commences, a predetermined amount of green sand is supplied to the louvered hopper 27 with the louvers 28 closed.

6. When the metal flask 5 has been loaded in preparation for the next molding and the supplying of green sand to the louvered hopper 27 has been completed, the coupled squeeze head 7 and louvered hopper 27 move, the table 9 rises in a state in which the louvered hopper 27 is arranged directly above the casting mold molding space, and molding of the next green sand mold commences.

In addition, pressure value data, casting mold strength data associated with pressure values, casting mold strength calculation results, and casting mold quality determination results, etc., which are produced during the molding step , are all recorded in the recording unit 22 of the casting mold quality evaluation device 12. Therefore, it is possible to use these numerical values to monitor the operational state of the casting mold molding device 1 and these numerical values are useful in quality control, maintenance, and troubleshooting of the casting mold molding device 1. Furthermore, using these numerical values can lead to early detection of defect causes such as: sand spillage, burn-in of a casting, and mold drop which occur due to loading defects; and swelling of a green sand mold due to molten metal pressure after pouring.

Furthermore, the data recorded in the recording unit 22 are recorded for each pattern attached to the plate 2. Therefore, it is possible to compare and examine a state, such as a defect in a green sand mold, with pressure value data, and setting of a more accurate threshold value becomes possible.

Further, in the present embodiment, a worker determines the expression y=ax+b by considering the slope “a” and the intercept “b” of the expression from the casting mold strengths and peak values of the pressure of the green sand mold molding sensors plotted on a graph. However, it is also possible to configure so that the casting mold strength calculation unit 18 automatically calculates the expression y=ax+b from the relationship between the casting mold strength and the peak value of the pressure of the green sand mold molding sensors by using a computer or a PLC and performing a linear regression by a least-squares method, etc.

Further, in the present embodiment, in the case that a molded green sand mold is determined to be a defect, a worker clarifies that the green sand mold in question is a defect. However, it is also possible to configure so that a determination result is automatically communicated to casting mold equipment of a subsequent step (molten metal pouring, etc.). In that case, at a subsequent step, the casting mold equipment automatically recognizes that the green sand mold in question is a defect, omits (skips) the step, and finally the green sand mold in question is shaken out from the mold.

Further, in the present embodiment, the green sand mold molding sensors 10A, 10B, 10C, 10D are embedded in the four corners of the squeeze board 8. However, even if the number of green sand mold molding sensors embedded in the squeeze board 8 is small, it is possible to calculate the relationship between the casting mold strength and the peak value of the pressure of the green sand mold molding sensors. In that case, accuracy is slightly lower in comparison with the case in which green sand mold molding sensors are embedded in four locations, but it is possible to curb costs.

In that case, it is also possible to embed green sand mold molding sensors at two locations on a line between opposing corners shown in FIG. 2: positions 10A and 10B; or 10C and 10D. FIGS. 14 and 15 show other examples of the squeeze board 8 having green sand mold molding sensors 10A, 10B embedded therein. 3 a shown by two-dot chain lines in these drawings shows a position in the casting mold molding space corresponding to the pattern 3 on the plate 2 having the pattern attached thereto. In FIG. 14, the two green sand mold molding sensors 10A, 10B are embedded near the central section of the long sides of the squeeze board 8. In FIG. 15, the two green sand mold molding sensors 10A, 10B are embedded near the central section of the short sides of the squeeze board 8.

In both cases, positions where the green sand mold molding sensors are embedded are positions corresponding to positions between the metal flask 5 and the pattern 3 in the casting mold molding space, in other words, between the metal flask 5 and the pattern 3 on the plate 2 having the pattern 3 attached thereto, and on the squeeze board or squeeze feet side facing a portion where there is no pattern on the plate 2.

Thus, the green sand mold sensor of the first embodiment makes it possible to measure a pressure value (peak pressure) applied to the pressing surface between the squeeze board 8 and green sand inside the casting mold molding space during molding of a green sand mold in order to determine the quality of a molded green sand mold.

Second Embodiment

Next, there follows a description of a second embodiment of the green sand mold molding sensor and the method for evaluating green sand mold moldability according to the present invention. Note that in the second embodiment described below, for configurations common with the first embodiment, the same reference signs are used in the drawings and descriptions thereof are omitted. In the second embodiment, a flaskless molding machine, rather than a flask molding machine, is used.

The second embodiment will be described with reference to the attached drawings. FIG. 16 represents a schematic of a structure of the casting mold molding device using green sand mold molding sensors according to the second embodiment and FIG. 17 represents a configuration of a portion of the casting mold molding device, wherein the portion evaluates casting mold quality. The casting mold molding device according to the present embodiment is a flaskless molding machine in which, after a green sand mold is molded, the green sand mold is removed from a casting flask.

A casting mold molding device 29 comprises the plate 2 having the pattern 3 attached to the upper and lower surfaces thereof, a shuttle dolly 30, a cope (metal flask) 31, a drag (metal flask) 32, an upper squeeze board 33, a lower squeeze board 34, the green sand mold molding sensors 10A, 10B, 10C, 10D embedded in the pressing surface of the upper squeeze board 33, green sand mold molding sensors 10E, 10F, 10G, 10H embedded in the pressing surface of the lower squeeze board 34, the wiring 11, and the casting mold quality evaluation device 12. Note that FIG. 17 represents the green sand mold molding sensors 10A, 10B, 10C, 10D embedded in the upper squeeze board 33 as seen when viewed from the line B-B of FIG. 16. Note also that the green sand mold molding sensors 10E, 10F, 10G, 10H are embedded in the lower squeeze board 34 and are thus shown at the same positions in FIG. 17. (Reference signs of the sensors when the lower squeeze board is viewed from the line C-C of FIG. 16 are shown in parentheses.)

The plate 2 has attached to the upper and lower sides thereof the pattern 3 for molding a shape of a casting in a green sand mold. The shuttle dolly 30 has the plate 2 placed thereon and makes round trips between the inside and the outside of the casting mold molding device 29 in accordance with the step. The cope 31 has green sand loaded therein in order to mold an upper mold of the green sand mold. In other words, the casting mold molding space surrounded by the cope 31, the upper squeeze board 33, and the plate 2 is loaded with green sand. The drag 32 has green sand loaded therein in order to mold a lower mold of the green sand mold. In other words, the casting mold molding space surrounded by the drag 32, the lower squeeze board 34, and the plate 2 is loaded with green sand. The upper squeeze board 33 and the lower squeeze board 34 are rectangular and are members that constitute a part of a boundary of a molding space defined by the members and, respectively, the cope 31 and the drag 32 during green sand mold molding by the casting mold molding device 29.

For the loading of green sand by the casting mold molding device 29, a blowing method that uses an airflow is employed. The blowing method is a method for loading green sand by blowing in green sand to the upper and lower surfaces of the plate 2 from green sand blowing-in ports 35, 35 of the cope 31 and drag 32.

The upper squeeze board 33 and the lower squeeze board 34 act via a cylinder (not shown), and the upper and lower green sand molds are molded simultaneously by tamping and compressing the green sand loaded in the cope 31 and the green sand loaded in the drag 32.

(Green Sand Mold Molding Sensor)

The green sand mold molding sensors 10A, 10B, 10C, 10D measure the pressure value (peak pressure) applied to the pressing surface between the upper squeeze board 33 and green sand loaded inside the cope 31 during molding of a green sand mold. The green sand mold molding sensors 10E, 10F, 10G, 10H measure the pressure value (peak pressure) applied to the pressing surface between the lower squeeze board 34 and green sand loaded inside the drag 32 during molding of a green sand mold. The green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H are pressure sensors. In the present embodiment, the green sand mold molding sensors 10A, 10B, 10C, 10D are embedded in the four corners of the pressing surface of the upper squeeze board 33. The green sand mold molding sensors 10E, 10F, 10G, 10H are embedded in the four corners of the pressing surface of the lower squeeze board 34. The reason that the green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H are embedded in such a way is the same as the reason described in the first embodiment.

In addition, the green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H have a pressure-receiving surface for measuring pressure that is exposed in pressing surface of the upper squeeze board 33 and the lower squeeze board 34 and measures the pressure value (peak pressure) applied to the pressing surface of the upper squeeze board 33 and the lower squeeze board 34. At this time, it is desirable for the pressure-receiving surface of the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H and the pressing surface of the upper squeeze board 33 and the lower squeeze board 34 to be in a flush state with no differences in level therebetween. Due thereto, it is possible to measure the precise pressure.

The wiring 11 connects the casting mold quality evaluation device 12 to the green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H. In the present embodiment, the green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H, and the casting mold quality evaluation device 12 are connected by wire via the wiring 11 but may also be connected wirelessly. For example, it is possible to use wireless communication such as a wireless LAN or Bluetooth, etc., to transmit the pressure value (pressure value data) detected by the green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H to the casting mold quality evaluation device 12.

The casting mold quality evaluation device 12 evaluates the quality of the green sand mold molded by the casting mold molding device 29 from the pressure value (pressure value data) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H. The casting mold quality evaluation device 12 comprises a receiving unit 15, an amplification unit 16, an input unit 17, a casting mold strength calculation unit 18, a casting mold quality determination unit 19, a display unit 20, a transmission unit 21, and a recording unit 22.

The receiving unit 15 receives the pressure value (pressure value data) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H. The amplification unit 16 amplifies the signal amount of the received pressure value (pressure value data). The input unit 17 inputs: the casting mold strength of a molded green sand mold, measured by a casting mold strength gauge; values of a slope “a” and an intercept “b” of the expression y=ax+b; and a threshold value of the casting mold strength of a green sand mold to be molded, etc.

From the casting mold strength inputted into the input unit 17 and the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D, and 10E, 10F, 10G, 10H, the casting mold strength calculation unit 18 uses the relational expression between the casting mold strength and the measurement values to calculate the casting mold strength for each pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H.

The casting mold quality determination unit 19 determines the quality of a molded green sand mold from the threshold value of the casting mold strength inputted into the input unit 17 and the calculated casting mold strength. The display unit 20 displays on a screen: the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H; values of the slope “a” and the intercept “b” of the relational expression y=ax+b between the casting mold strength inputted by a worker using the input unit 17 and the pressure value (peak pressure); the threshold value of the casting mold strength of a green sand mold to be molded that was inputted by a worker; the casting mold strength calculation result; and the casting mold quality determination result, etc.

The transmission unit 21 transmits fault-determination data to the Patlite 23, etc. The recording unit 22 records pressure value data, casting mold strength data associated with pressure values, casting mold strength calculation results, and casting mold quality determination results, etc.

(Method for Evaluating Casting Mold Quality Using Casting Mold Molding Device)

Next, there follows a description of a method for evaluating casting mold quality (method for molding a green sand mold) using the casting mold molding device 29. FIG. 18 shows steps in a method for evaluating casting mold quality (method for molding a green sand mold) using the casting mold molding device 29 according to the second embodiment. Note that in FIG. 18, a sand tank 36 is adjacent to the casting mold molding device 29 shown in FIG. 16. A predetermined amount of green sand is loaded into the sand tank 36 from the green sand transportation device (not shown) and, after having been briefly retained, a loading hole is closed and when compressed air is supplied inside the sand tank 36, green sand is loaded by being blown into the upper and lower casting mold molding spaces via green sand blowing-in ports 35, 35 in the cope 31 and the drag 32.

Molding of a green sand mold by the casting mold molding device 29 follows the procedure described below.

1. When molding commences, from the state shown in FIG. 18(a), the shuttle dolly 30 having placed thereon the plate 2, which has the patterns 3, 3 attached thereto, moves between the cope 31 and the drag 32.

2. Next, the lower squeeze board 34, which has the green sand mold molding sensors 10E, 10F, 10G, 10H embedded therein, and the drag 32 rise, lift the plate 2 from the shuttle dolly 30, and when the state shown in FIG. 18(b) is set, compressed air is supplied to the sand tank 36 and green sand is loaded by being blown into the upper and lower casting mold molding spaces via the green sand blowing-in ports 35, 35 in the cope 31 and the drag 32.

3. Next, due to the action of a cylinder (not shown), the upper and lower squeeze boards 33, 34, which have the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H embedded therein, squeeze (compress) the green sand inside the cope 31 and the drag 32 and the state shown in FIG. 18(c) is achieved. At this time, the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H measure the pressure value (peak pressure) at the pressing surface of the upper and lower squeeze boards 33, 34. Note that green sand molds are molded in the present step. At this time, the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H are between the pattern 3 and the wall of, respectively, the cope 31 of the upper squeeze board 33 and the drag 32 of the lower squeeze board 34. At this time, the measured pressure value (peak pressure) is transmitted to the casting mold quality evaluation device 12 and the quality of the green sand mold that has just been molded is evaluated.

Quality evaluation by the casting mold quality evaluation device 12 is performed after the expression y=ax+b, which represents the relationship between casting mold strength and the peak value of the pressure of the green sand mold molding sensors, has been determined in advance. In addition, a green sand mold determined to be OK by the casting mold quality evaluation device 12 flows, as-is, along the line and subsequent steps (molten metal pouring, etc.) are carried out. Meanwhile, a green sand mold determined to be faulty by the casting mold quality evaluation device 12 flows, as-is, along the line, but subsequent steps (molten metal pouring, etc.) are not carried out. The green sand mold skips these steps and, as a casting mold to be discarded, is shaken out from the mold in the same way as a green sand mold for which the casting mold quality is determined to be OK.

4. Next, the lower squeeze board 34 and the drag 32 lower and when the plate 2 is placed on the shuttle dolly 30, a state in which the patterns 3, 3, are removed from the upper and lower green sand molds is reached. Then, the shuttle dolly 30 moves to the position shown in FIG. 18(a) and when the lower squeeze board 34 and the drag 32 rise again, mold alignment of the upper and lower green sand molds is carried out by aligning the cope 31 and the drag 32. At this time, the upper and lower green sand molds are in a state of being sandwiched by the upper squeeze board 33 and the lower squeeze board 34. From this state, when the upper squeeze board 33 and the lower squeeze board 34 lower, the aligned upper and lower green sand molds are lowered and removed from the cope 31 and the drag 32 to reach the state shown in FIG. 18(d).

5. The aligned upper and lower green sand molds are transported from the casting mold molding device 29 to a line of the next step.

In addition, pressure value data, casting mold strength data associated with pressure values, casting mold strength calculation results, and casting mold quality determination results, etc., which are produced during the molding step , are all recorded in the recording unit 22 of the casting mold quality evaluation device 12. Therefore, it is possible to use these numerical values to monitor the operational state of the casting mold molding device 29 and these numerical values are useful in quality control, maintenance, and troubleshooting of the casting mold molding device 29. Furthermore, using these numerical values can lead to early detection of defect causes such as: sand spillage, burn-in of a casting, and mold drop which occur due to loading defects; and swelling of a green sand mold due to molten metal pressure after pouring.

Further, in the present embodiment, the green sand mold molding sensors 10A, 10B, 10C, 10D and 10E, 10F, 10G, 10H are embedded in the four corners of the pressing surface of the upper and lower squeeze boards 33, 34 near the cope 31 and the drag 32. However, even if the number of green sand mold molding sensors embedded in the upper and lower squeeze boards 33, 34 is small, it is possible to calculate the relationship between the casting mold strength and the peak value of the pressure of the green sand mold molding sensors. In that case, accuracy is slightly lower in comparison with the case in which green sand mold molding sensors are embedded in four locations, but it is possible to curb costs.

In that case, it is also possible to set two locations 10A, 10B or 10C, 10D on a line between opposing corners of the pressing surface of the upper squeeze board 33 shown in FIG. 17 or to set two locations 10E, 10F or 10G, 10H on a line between opposing corners of the pressing surface of the lower squeeze board 34. FIGS. 19 and 20 show other examples wherein the pressing surface of the upper squeeze board 33 has green sand mold molding sensors 10A, 10B embedded therein. 3a shown by two-dot chain lines in these drawings shows a position in the casting mold molding space corresponding to the pattern 3 on the plate 2 having the pattern attached thereto. In FIG. 19, the two green sand mold molding sensors 10A, 10B are embedded near the central section of the long sides of the upper squeeze board 33. In FIG. 20, the two green sand mold molding sensors 10A, 10B are embedded near the central section of the short sides of the upper squeeze board 33. It is possible to arrange the molding sensors 10E, 10F in the same state in the pressing surface of the lower squeeze board 34. Due to the arrangement of these molding sensors, it is possible to ascertain a bias in the loading amount, etc., between right and left of the green sand blowing-in ports 35, 35, or in the proximity or distance of the green sand blowing-in ports 35, 35.

Thus, the green sand mold molding sensor according to the second embodiment makes it possible to measure the pressure value (peak pressure) applied to the pressing surface between the upper squeeze board 33 and green sand loaded inside the cope 31 and the pressure value (peak pressure) applied to the pressing surface between the lower squeeze board 34 and sand loaded inside the drag 32 during molding of a green sand mold in order to determine the quality of a molded casting.

(Modifications)

In the first and second embodiments, after determining the relationship between the casting mold strength and the pressure value (peak pressure) from the measured casting mold strength and the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D (and 10E, 10F, 10G, 10H), the casting mold quality evaluation device 12 separately calculates the casting mold strength from the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D (and 10E, 10F, 10G, 10H). In addition, the quality of a molded green sand mold is determined from the pre-set threshold value of the casting mold strength and the calculated casting mold strength.

Additionally, by feeding back results determined by the casting mold quality evaluation device 12 to a kneading machine, it is possible to accurately control the amount of water injected into the kneading machine. For example, if the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D (and 10E, 10F, 10G, 10H) is extremely low and as a result thereof the casting mold strength is extremely low, the casting mold quality evaluation device 12 determines that the reason therefor is because sand was not loaded evenly inside the casting mold and that the cause thereof is that the CB value of the green sand is high, and by providing an instruction to the kneading machine to reduce the amount of water injected, it is possible to resolve the loading defect of the green sand.

Furthermore, by feeding back, to the kneading machine, results determined by the casting mold quality evaluation device 12 and results obtained by a green sand automatic measurement system, or the like, measuring and evaluating the compressive strength of the green sand, it is also possible to control the amount of additives, water, etc., loaded into the kneading machine. For example, it is possible to perform an evaluation of the flowability, etc., of the green sand from: properties of the green sand measured by the green sand automatic measurement system such as the compressive strength, permeability, compactability value, water content value, etc. of the green sand; the pressure value (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D (and 10E, 10F, 10G, 10H); and the distribution thereof. Further, by changing the amount of additives, water content, etc., loaded during kneading, it is possible to resolve casting mold defects.

Furthermore, in the first and second embodiments, the casting mold quality evaluation device 12 converts measured casting mold strengths and the pressure values (peak pressure) measured by the green sand mold molding sensors 10A, 10B, 10C, 10D (and 10E, 10F, 10G, 10H) into the casting mold strength and determines the quality of molded green sand molds from that casting mold strength. However, since it has been ascertained that there is a correlative relationship between the pressure value (peak pressure) and the casting mold strength, it is also possible to determine the quality of a green sand mold directly from the pressure value (peak pressure) without converting to the casting mold strength.

Third Embodiment

FIG. 21(a) is a vertical cross-section view of a casting mold molding device using green sand mold molding sensors that is a third embodiment of the present invention. FIG. 21(b) shows squeeze feet when viewed from line D-D. Note that in the third embodiment described below, for configurations common with the first embodiment, the same reference signs are used in the drawings and descriptions thereof are omitted. In the third embodiment, squeeze feet, rather than a squeeze board, are used. In the drawings, the reference sign 300 refers to squeeze feet. The squeeze feet 300 are arranged rectangularly and are members that constitute a part of a boundary of a molding space defined by the squeeze feet 300 and the metal flask 5 during green sand mold molding by the casting mold molding device 1. As shown in FIG. 21(b), green sand mold molding sensors 10I, 10J, 10K, 10L are embedded in individual squeeze feet.

The embodiment shown in these drawings differs from the first embodiment described above in that the squeeze feet 300 are used as elements that perform the squeezing action. With respect to these squeeze feet 300, by vertically positioning the squeeze feet 300 facing the pattern 3 according to the height of the pattern 3 and moving the squeeze feet 300 during the squeezing action, the height of the loaded green sand is adjusted and the tamping pressure is controlled to be the same at all squeeze feet upon completion of the squeezing.

As shown in FIG. 21(a) for example, squeeze feet 300 b, 300 d, which face high sections of the pattern 3, are positioned so as to protrude further toward the pattern 3 than do squeeze feet 300 a, 300 c, 300 e, which face low sections of the pattern 3. When a casting mold molding space is subsequently defined and green sand is loaded with the positions of these squeeze feet 300 a-300 e kept as-is (not shown), the amount of sand directly below the squeeze feet 300 b, 300 d can be made smaller than the amount of sand directly below the squeeze feet 300 a, 300 c, 300 e (not shown). From this state, while a squeeze head 7 is lowered, the squeeze feet 300 a-300 e are moved to positions where ultimately all the surfaces facing the pattern 3 are aligned and the squeezing step ends. By controlling the squeeze feet in such a way, it is possible to achieve a uniform compression rate of green sand irrespective of the sectional difference in height of the pattern 3 (not shown).

Further, preliminary observations are made of the tendency of a loading state of green sand, not only of the height of the pattern, and the vertical positions of the squeeze feet 300 may be adjusted in line with a non-uniformity in the loading of the green sand. By controlling the squeeze feet in such a way, even when there is a pattern or even when there is a non-uniform tendency in sand loading before squeezing, it is possible to move the squeeze feet by means of cylinders that cause vertical movement, during green sand loading and during squeezing, such that the squeeze feet perform tamping with equal force. That is, it is possible to mitigate “non-uniformity in sand introduction” (biases in the density distribution of loading of green sand before tamping and in the loading height of green sand before tamping) due to the patterns, which was a drawback of using the squeeze board.

When a casting mold has been managed and molded normally through the above movements, the (peak) pressure values measured by the green sand mold molding sensors embedded in the squeeze feet 300 are equal at all the sensors. As such, when a measured pressure value during molding lies outside the variation in values observed in a normal state, it is believed that an abnormality has occurred due to some kind of cause.

These causes are believed to include extremely non-uniform sand introduction and malfunctioning of the cylinders that move the squeeze feet.

Cases where the variation in these pressure values has become large are regarded as cases where a peculiar variation has occurred, and the casting molds are determined and processed as FT in the casting mold quality evaluation device.

A method for determining a peculiar variation herein may be, for example, a case where a standard deviation in the pressure values measured by a plurality of green sand mold molding sensors embedded in the squeeze feet during molding of one casting mold is calculated, and the standard deviation is greater than a predetermined reference value. This reference value may be arbitrarily set and, for example, may be initially set as a value considered appropriate in terms of casting mold quality.

Further, it is also possible to deem a peculiar variation as being a case in which a variation is greater, by 20% or more, than the average value of the standard deviations of pressure values measured for casting molds molded in the preceding 10 flasks. The number of previously molded casting molds to be subjected to average calculations and the ratio of the extent by which the average is exceeded, which is a determination reference for peculiar variations, can be selected as appropriate herein.

In this embodiment, other than the points described above, casting mold molding is performed through the same movements as those of the first embodiment, and the same functions and effects as those of the first embodiment mentioned above are obtained.

The abovementioned first, second, and third embodiments are examples where two or more pressure sensors were provided in the squeeze board or squeeze feet. However, in the present invention, a configuration in which one pressure sensor is provided to the squeeze board or squeeze feet is also possible. In that case, it is desirable that the position at which the pressure sensor is attached is near the pattern of the plate. Further, in such cases when there is one pressure sensor, the output of the one pressure sensor also indicates a value related to the casting mold strength at a specific position of the casting mold. Therefore, accuracy decreases but it is possible to use this value to perform an evaluation of the casting mold quality.

Various embodiments of the present invention are described above, but the above descriptions do not limit the present invention and various modifications may be considered, including deletion, addition, and replacement of constituent elements within the technical scope of the present invention.

REFERENCE SIGNS LIST

-   1 Casting mold molding device (flask casting mold molding) -   2 Plate -   2 a Central plate -   2 b Peripheral plate -   3 Pattern -   4 Carrier -   5 Metal flask -   6 Filling flask -   7 Squeeze head -   8 Squeeze board -   9 Table -   10A-10L Green sand mold molding sensor -   11 Wiring -   12 Casting mold quality evaluation device -   13 Liner -   14 Bolt -   15, 15′ Receiving unit -   16, 16′ Amplifying unit -   17 Input unit -   18 Casting mold strength calculation unit -   19 Casting mold quality determination unit -   20 Display unit -   21 Transmission unit -   22 Recording unit -   23 Patlite -   24 Pressure value transmission unit -   25 Integrated amplifier-recorder -   26 Computer -   27 Louvered hopper -   28 Louver -   29 Casting mold molding machine (flaskless molding machine) -   30 Shuttle dolly -   31 Cope -   32 Drag -   33 Upper squeeze board -   34 Lower squeeze board -   35 Green sand blowing-in port -   36 Sand tank -   300, 300 a-300 e Squeeze foot 

1. A casting mold molding machine comprising a green sand mold molding sensor comprising at least one pressure sensor for evaluating moldability of a green sand mold molded by the casting mold molding machine, a squeeze board or squeeze feet that compress green sand, and a mold pattern, wherein the green sand is compressed between the mold pattern and the squeeze board or squeeze plate, wherein the at least one pressure sensor is embedded in the squeeze board or squeeze feet that compress green sand, and wherein a pressure-receiving surface of each of the at least one pressure sensors and a surface of the squeeze board or squeeze feet are in a flush state.
 2. The casting mold molding machine according to claim 1, wherein the squeeze board or squeeze feet is a member that constitutes a part of a boundary of a molding space defined by the squeeze board or squeeze feet and a metal flask during green sand molding by the casting mold molding machine.
 3. The casting mold molding machine according to claim 1, wherein, as a member that constitutes a part of a boundary of a molding space defined by the member and a metal flask during green sand mold molding by the casting mold molding machine, the squeeze board or squeeze feet and a plate having attached thereto the mold pattern arranged facing the squeeze board or squeeze feet are provided, each of the at least one pressure sensors being embedded at a corresponding position in the squeeze board or squeeze feet between the metal flask and the mold pattern.
 4. The casting mold molding machine according to claim 1, wherein the squeeze board is configured to be rectangular, a plurality of the pressure sensors are provided, and each of the four corners of the rectangular squeeze board has embedded one of the plurality of pressure sensors.
 5. The casting mold molding machine according to claim 1, wherein an arrangement of the squeeze feet is configured to be rectangular, a plurality of the pressure sensors are provided, and the plurality of the pressure sensors are embedded in any of the squeeze feet including the squeeze feet in the four corners.
 6. The casting mold molding machine according to claim 1, wherein the at least one pressure sensor is fixed to the squeeze board or squeeze feet by a screwing means.
 7. The casting mold molding machine according to claim 1, wherein the at least one pressure sensor is a fluid sensor.
 8. The casting mold molding machine according to claim 1, wherein the at least one pressure sensor has a pressure-receiving surface that is 5-30 mm in diameter. 